Reduced vulnerability munitions (known as MURAT for MUnition with Risk ATtenuation), developed a decade and a half ago, necessitate the use of explosive molecules of little or no sensitivity. These molecules are required to possess a sensitivity which is as low as possible, while retaining a heightened level of energetic performance. But these two properties are difficult to reconcile. For instance, cyclotetramethylene tetranitramine (octogen) is the most widespread explosive to date, but has a level of insensitivity (essentially to impact) which is inadequate for application to MURAT-type munitions. 3-Nitro-1,2,4-triazol-5-one (ONTA), for its part, is an energetic molecule which is entirely exceptional in terms of insensitivity, being markedly less sensitive than octogen, for example. On the other hand, its level of energetic performance is lower than that of octogen. The same is true of other low-sensitivity explosive molecules, such as 1,3,5-triamino-3,4,6-trinitrobenzene (TATB), 1,1′-diamino-2,2′-dinitroethylene (FOX-7) or 4,6-di-(3-amino-5-nitro-1,2,4-triazole)-5-nitropyrimidine (FR 2,624,118).
The skilled worker is constantly looking for new energetic molecules which offer an advantageous tradeoff in terms of performance and vulnerability while retaining a level of thermal stability that meets the demands of the application. Such molecules advantageously exhibit characteristics of thermodynamic decomposition that allow them to be used in the fields of propulsion and of explosives.
Lebedev et al. showed calculated and/or measured results of physico-chemical properties and of performances for energetic compounds (INTERNATIONAL ANNUAL CONFERENCE OF ICT, vol. 29, 1 janvier 1998, p. 180.1-180.13). The developed chemical formulae of said compounds together with said results are shown in Tables. It has to be emphasized that the synthesis (that any process for the preparation) of the concerned compounds, more particularly the one of compounds of formula VII, VIII, IX, are neither disclosed, nor suggested. To the inventor's knowledge, no additional information has since been published related to these compounds and their process of preparation, except information on 4-amino-3,5-dinitro-1-pyrazole (compound of formula IX) (see the following paragraph). The inventor notably discloses a non obvious process for the preparation of the 5-amino-3,4-dinitro-1-pyrazole further in the present text (within the scope of the present invention).
R. D. Schmidt, G. S. Lee, P. F. Pagoria, A. R. Mitchell and R. Gilardi, in J. Heterocyclic Chem. 2001, 38, 1227, described the synthesis and properties of a new explosive: 4-amino-3,5-dinitro-1-pyrazole (LLM-116). This new explosive is presented as being advantageous in reference to the tradeoff referred to above: sensitivity/performance. Nevertheless, it has the major disadvantage of dissolving small polar organic molecules such as DMSO and of undergoing hydration in the presence of water. However, the product is advantageous, in performance terms, only if it is free from any trace of impurity, and the purification and dehydration process is long and laborious.
The skilled worker is therefore still looking for new energetic molecules which comply with the specification set out above and which, furthermore, advantageously, can be synthesized readily.